Multi-station RF thermometer and alarm system

ABSTRACT

A multi-station RF thermometer and alarm system measures temperatures and/or percent relative humidity at remote locations by RF weather stations, and displays received temperature and/or other weather data telemetry on a multi-station base station that provides out-of-bounds alarm signal indications whenever temperatures are outside of user-selectable minimum and maximum values. Randomized transmission times in one embodiment and two-phase unique transmission schedules in another lessen the possibility of on-going collisions between two or more transmitters contending for the base station at the same time. Redundant data transmission lessens the possibility of environmental noise interference. The redundant data, transmitted at random times in one embodiment, includes a unique channel ID code, house-keeping data, the current temperature and/or time-to-next-transmission data, and in another embodiment, transmitted at uniquely prescheduled times of two-phase transmission schedules, includes station location ID and transmission schedule phase. The weather parameter sensing transmitters operate at a low duty cycle with low peak current consumption resulting in long battery life. The multi-station base station may be AC- or battery-powered. Channel and station ID switches are provided on the remote temperature sensing transmitters and on the multi-station base station in one embodiment and a station ID number selection switch is provided in another transmitter embodiment.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This invention is a division of allowed continuation-in-partapplication Seri. No. 09/421,974 filed Oct. 20, 1999, which is acontinuation of U.S. utility patent application Ser. No. 08/968,290filed Nov. 12, 1997, now U.S. Pat. No. 6,046,674, each incorporatedherein by reference.

FIELD OF THE INVENTION

[0002] This invention is drawn to the field of telemetry, and moreparticularly, to a novel multi-station RF thermometer and alarm system.

BACKGROUND OF THE INVENTION

[0003] Many of life's activities are heavily influenced by thetemperature. Heretofore, hard-wired digital thermometers, such as themodel IOTA1 and the model IOTA2 commercially available from TRENDIndustries, Inc., or the Electronic Weather Station With Alarm Clock,commercially available from CATHAY PACIFIC, measure temperature by ahard-wired probe, and display the measured temperature on an associateddisplay. Such hard-wired digital thermometers, however, need to beplaced within inches or feet of the environment to be measured. This canbe inconvenient, as this type of digital thermometer is not placed whereit is most accessible and likely to be needed (e.g., next to a bed, on adesk, etc.), but where it must be placed to work.

[0004] Wireless (RF) digital thermometers, such as the model “7055”Wireless Weather Station With Radio Controlled Clock, commerciallyavailable from Europe Supplies, Ltd., measure temperature by a remotewireless temperature station and display the measured temperature on adisplay associated with a base station. Although in principle suchtransmitters may be remotely located to the base, environmental noisesources have generally limited their practical range and have given riseto erroneous telemetry and lack of operator confidence. And if more thanone location needs to be monitored, another such RF transmitter and basepair needs to be provided for every location to be measured. Not onlyhas this resulted in increased overall costs, and undesirablemultiplication of base stations, but the utility of suchtransmitter/base pairs has further been limited by contention-inducedinterference as transmissions from the multiple transmitters collide ateach base station.

[0005] Moreover, both the hard-wired and RF temperature thermometersheretofore have had their utility limited by probe placementdifficulties, whenever locations that are other than directly exposedand in the open are to be monitored, and by a general inability toprovide information of comfort level or of weather situations that mayendanger well-being.

SUMMARY OF THE INVENTION

[0006] Accordingly, it is an object of the present invention to disclosea multi-station RF thermometer and alarm system suitable for home,office and light industrial use.

[0007] It is another object of the present invention to disclose amulti-station RF thermometer and alarm system that provides temperaturemonitoring of plural remote locations and at a local base station.

[0008] It is another object of the present invention to disclose amulti-station RF thermometer and alarm station that provides reliabletemperature or other weather parameter, such as humidity, transmissionand reception in the presence of interference (environmental noiseinterference and contention-induced interference).

[0009] It is another object of the present invention to disclose amulti-station RF thermometer and alarm system that provides user-setablealarm limits for each of multiple remote and/or local locations and thatprovides alarm signals whenever out-of-bounds conditions prevail at anylocation.

[0010] It is another object of the present invention to disclose amulti-station RF thermometer and alarm system that provides accuratetemperature or other weather parameter, such as humidity, sensing andtransmission over wide temperature, humidity and distance ranges in amanner that requires low power consumption suitable for long-lifebattery operation.

[0011] It is another object of the present invention to disclose amulti-station RF thermometer and alarm system that responds totemperature and humidity telemetry and provides heat index informationnot only useful as a general comfort indicator, but may also proveinvaluable in times when high temperature and high humidity can lead todangerous heat stroke levels.

[0012] In accord therewith, the disclosed multi-station RF thermometerand alarm system of the present invention includes at least oneportable, battery-powered temperature station and a multi-station basestation. Each of the at least one portable, battery-powered temperaturestations provides, as desired, measurement of temperatures in rooms,refrigeration devices, pools, outdoor areas, etc., and the multi-stationbase station, which may be placed on a desk, at bedside, or otherwise asconvenient, receives and displays, preferably concurrently, the measuredtemperature data received from the one or more portable, battery-poweredtemperature stations and measured at the multi-station base station.

[0013] In one preferred embodiment, each temperature station transmitsremote temperature measurements over a two-hundred and fifty foot (250′)range to the multi-station base station and is operable over an activeindoor/outdoor temperature range from minus forty degrees (−40) OF toone hundred and fifty eight (158)OF. In this embodiment, themulti-station base station receives and displays temperature from up tofour (4) remote transmitters.

[0014] Accordingly to one aspect of the present invention, the portable,battery-powered temperature station includes an analog temperaturesensor providing a temperature signal representative of sensedtemperature; an antenna; and a processor-controlled transmitter coupledto the antenna and to the temperature signal operative (1) toperiodically convert the temperature signal to a digital representationof the sensed temperature, (2) to digitally encode a data frame havingfirst information representative of the sensed temperature and secondinformation representative of station ID, and (3) to transmit apredetermined integral number greater than one (1) of data frames eachhaving said first and said second information at a random time. Therandomized transmission times, and redundantly encoded temperature andtransmitter ID data, cooperate to alleviate collision-induced contentionand to provide reliable data transmission in noisy environments. In thisembodiment, the temperature data is read every thirty (30) seconds andfive (5) redundant data frames are randomly transmitted once everythirty (30) to sixty (60) seconds.

[0015] Accordingly to a further aspect of the present invention, theportable, battery-powered temperature station includes an analogtemperature sensor providing a temperature signal representative ofsensed temperature; an antenna; and a processor-controlled transmittercoupled to the antenna and to the temperature signal operative (1) toperiodically convert the temperature signal to a digital representationof the sensed temperature, (2) to generate a schedule of present andfuture random transmission times, (3) to digitally encode a data framehaving first information representative of the sensed temperature,second information representative of station ID, and third informationrepresentative of the schedule of present and future random transmissiontimes and (4) to transmit a predetermined integral number of data frameseach having said first, said second and said third information at arandom time. The schedule of present and future random transmissiontimes allows the multi-station base station to “sleep” at times when notransmissions are scheduled, or when previous transmissions indicatevery little temperature change, thereby conserving power enablinglong-life battery-powered base station operation.

[0016] According to another aspect of the present invention, thedisclosed portable, battery-powered temperature station includes ahousing; a waterproof probe electrically connected to the housing via anelongated flexible cable of predetermined length; an attachment memberfor stowing the probe to the housing when not in use; and means forpaying out any selected length of the elongated flexible cable ofpredetermined length selected to accommodate the needs of eachparticular application. In one preferred embodiment, the housingincludes a front wall and a battery receiving compartment, and theattachment member includes a well formed in the front wall of thehousing dimensioned to frictionally receive the probe, and the pay-outmeans includes a wire-receiving chamber provided in the batterycompartment of the housing. The selectably extendable probe enables tomeasure hard-to-reach areas, such as the water temperature of an outdoorpool or the inside temperature of a storage freezer.

[0017] According to another aspect of the present invention, thedisclosed multi-station base station includes a multi-fieldreconfigurable display; operator input means; a receiver for providingan output signal in response to transmissions received from each atleast one portable, battery-powered temperature station; and a processorcoupled to the display, to the input means, and to the receiver, that isoperative in a decode/display mode, an alarm set mode, and an alarmannounce mode.

[0018] In the decode/display mode, the processor is operative (1) toconfigure the display with a field that corresponds to each of multipletemperature station zones, (2) to recover from the output signal of thereceiver the first information representative of sensed temperature andthe second information representative of the transmitting station ID foreach data frame of the redundantly transmitted data frames, and (3) todisplay the recovered temperature data in a field corresponding to anidentified station if the first information representative of the sensedtemperature of two (2) of the redundantly transmitted data framesconform to each other for a given station.

[0019] In one preferred embodiment, the display is configured with acomparatively-large “active” location field, with five (5) temperaturestation fields (four (4) remote station and one (1) base stationfields), and with temperature high and low fields, and the processor isoperative in the decode/display mode to display the current temperatureof any temperature station in the comparatively large “active” locationfield and the daily high and low temperatures in the corresponding highand low temperature fields in response to operator input stationselection, and to concurrently display the temperature at any activelocations (remote and/or base) in the corresponding ones of the five (5)temperature station fields. Other display configurations, such asconcurrent and/or sequential display of less than all of the activelocations, and operator input station display selection, could beemployed.

[0020] In the alarm set mode, the processor is operative to configurethe display with alarm min and alarm max fields and with at least onealarm set station field, and is operative in response to operator inputstation (base or remote) selection, in response to operator input alarmmin and max values selection and in response to operator input alarmarming to set and to display min and max temperature bounds for eachstation selected and armed. Min/max setpoints for temperature range maybe set for all locations. If the temperature in any location goesoutside this set range, an alarm (visible, audible and/or remote) signalindication is provided in alarm announce mode. In the preferredembodiments, all stations that have been armed are concurrentlydisplayed, although sequential display in response to operator inputstation display selection could be employed.

[0021] In alarm announce mode, the processor is operative to configurethe display with an alarm announce icon field and at least one activealarm station field, and is operative (1) to display a location where anactive alarm condition exists in the active alarm station field, (2) toprovide an alarm signal indication, and (3) is operative in response tooperator alarm dis-arm input to clear the alarm condition for each alarmlocation. The alarm signal may be an audible, a visible, and/or a remotealarm signal. In the preferred embodiments, all stations that haveactive alarm conditions are concurrently displayed, although sequentialdisplay in response to operator input station display selection could beemployed.

[0022] In one embodiment, the multi-station base station is AC outletpowered, and in other embodiments, it is battery-powered.

[0023] In further disclosed embodiments, each portable, battery-poweredweather station is operative to alternatively transmit percent relativehumidity and temperature data redundantly in accord with a schedule oftransmission times unique to each portable, battery-powered weatherstation. The redundant transmission of weather data helps prevent noiseinterference at the multi-station base station, and the unique schedulesof transmission times both held prevent contention-induced interferenceat the multi-station base station as well as allow the multi-stationbase station to enter battery-power-conserving mode when no receptionsare scheduled from each of the portable weather stations.

[0024] For each of the portable, battery-powered weather stations thatmeasure and transmit temperature and percent relative humidity data, themulti-station base station selectably calculates and displays heat indexinformation.

[0025] A method of encoding data at the portable, battery-poweredweather stations to maximize transmission range and detectionsensitivity at the battery-powered multi-station base station isdisclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] These and other objects, inventive aspects, and advantageousfeatures will become apparent as the invention becomes better understoodby referring to the following detailed description of the presentlypreferred embodiments, and to the drawings, wherein:

[0027]FIG. 1 is a functional block diagram of the multi-station RFthermometer and alarm system of the present invention;

[0028]FIG. 2 is an elevational view of the front of one embodiment ofthe portable, battery-powered temperature station of the presentinvention;

[0029]FIG. 3 is a perspective view of the back of the portable,battery-powered temperature station of the present invention with thebattery door and wall mounting bracket removed;

[0030]FIG. 4 is a functional block diagram of the portable,battery-powered temperature station of the multi-station RF thermometerand alarm system of the present invention;

[0031]FIG. 5 is a diagram illustrating the data format of the portable,battery-powered temperature station of the present invention;

[0032]FIG. 6 is a schematic circuit diagram of the RF oscillator of theportable, battery-powered temperature station of FIG. 4;

[0033]FIG. 7 is a flow chart of the processor of the portable,battery-powered temperature station of FIG. 4;

[0034]FIG. 8 is a front elevational view of one embodiment of themulti-station base station of the multi-station RF thermometer and alarmsystem of the present invention;

[0035]FIG. 9 is a functional block diagram of the multi-station basestation of the present invention;

[0036]FIG. 10 is a schematic circuit diagram of the receiver of themulti-station base station of FIG. 9;

[0037]FIG. 11 is a state diagram of the processor of the multi-stationbase station of FIG. 9;

[0038] FIGS. 12-14 are pictorial diagrams illustrating the multi-fieldreconfigurable display of the multi-station base station of FIG. 9respectively configured in decode/display mode, alarm set mode and alarmannounce mode;

[0039]FIG. 15 is a flow chart of the processor of the multi-station basestation of FIG. 9;

[0040]FIG. 16 is an elevational view of the front of another embodimentof a portable, battery-powered weather station of the present invention;

[0041]FIG. 17 is a functional block diagram of the portable,battery-powered weather station of the multi-station RF thermometer andalarm system of the present invention;

[0042]FIG. 18 is a diagram illustrating the data format of the portable,battery-powered weather station of the present invention;

[0043]FIG. 19 is a flow chart of the processor of the portable,battery-powered weather station of FIG. 17;

[0044]FIG. 20 illustrates in the FIGS. 20A-20C thereof front elevationalviews of another embodiment of a battery-powered multi-station basestation of the multi-station RF thermometer and alarm system of thepresent invention for use with the portable, battery-powered weatherstation of FIGS. 16-19;

[0045]FIG. 21 is a functional block diagram of the multi-station basestation of the present invention;

[0046]FIG. 22 is a state diagram of the processor of the multi-stationbase station of FIG. 21; and

[0047]FIG. 23 is a flow chart of the processor of the multi-station basestation of FIG. 21.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0048] Referring now to FIG. 1, generally designated at 10 is afunctional block diagram of the multi-station RF thermometer and alarmsystem in accord with the present invention. The system 10 includes aplurality of RF thermometers or other weather stations 12 to bedescribed and a multichannel base station 14 in spaced apart relation tothe plural RF thermometers 12. The system 10 is adapted for home, officeand light industrial use. The RF thermometers 12 are portable,battery-powered devices that may be placed anywhere where temperaturesare to be monitored. For example, one temperature transmitter 12 couldbe attached to the back of the house, another in the pool, a third in agreen house, and a fourth in the garden, not shown. The multi-channelbase station 14 includes a receiver, not shown, to be described thatreceives the temperatures or other weather data transmitted by theplural RF thermometers 12 and displays temperature data received fromthe plural RF thermometers 12 on display 16. The multichannel basestation 14 also displays the temperature at the base station by means ofthe display 16. In the presently preferred embodiments, the display 16displays the temperature at the base station 14, as well as thetemperatures at each of the remote RF thermometers 12, concurrently.Other temperature display methodologies, such as sequential display ofthe temperatures at plural remote and base station locations may beemployed.

[0049] The multichannel base station 14 monitors the temperature datareceived from each of the plural remote RF thermometers 12 and the basestation 14 and compares the received temperatures and the base stationtemperature to user-setable alarm limits to be described for each remotelocation and the base station. In the preferred embodiments, the alarmlimits are minimum and maximum limits independently user setable foreach location (base and remote). If the received temperatures and thelocal base station temperature are out of the bounds set by the alarmlimits for any location, the multichannel base station 14 provides analarm as schematically illustrated by box 18. The alarm 18 in thepreferred embodiment includes an audible and a visible alarm signal.

[0050] A remote dialer 20 is connected to the multichannel base station14. The remote dialer 20 is connected to a remote station 22 via thephone network 24. The remote dialer 20 sends all temperature data to theremote display 22 at preset times, or when alarm conditions exist at anylocation.

[0051] The remote station 22 receives and displays all temperature orother data sent by the remote dialer 22. The remote station 22 may dialthe remote dialer 20 via the phone network 24 to request the currenttemperature data for any location, as well as the corresponding alarmlimits.

[0052] The remote station 22 preferably includes a DTMF generator and aDTMF listener, not shown, that cooperate to send control information viathe phone lines, and to receive data back from the multi-station basestation in accord with the control information sent. The remote userinto this way may, for example, request the current temperatureinformation from all stations (remote and base) from the multi-stationbase station.

[0053] To manage interference (contention-based interference arisingfrom the plural RF thermometers competing with the multichannel basestation as well as noise interference arising in the intended operatingenvironment), the multi-station RF thermometer and alarm system 10 ofthe present invention employs four (4) principal measures. First, eachRF thermometer 12 and the multichannel base station 14 in one embodimentare provided with dual, user selectable channels “A” and “B” to bedescribed. For example, interference from another multi-station RFthermometer and alarm system operating in the same locale may beeliminated by switching from one to the other of the two (2) channels.Second, each RF thermometer 12 in one embodiment transmits itstemperature data at random times, preferably once every thirty (30) tosixty (60) seconds. The randomness of the transmissions makes itstatistically unlikely that temperature data from multiple RFthermometers arrive simultaneously at the multichannel base station 14.In another embodiment, each RF weather station 12 transmits itstemperature and/or humidity data in accord with a schedule oftransmission times unique to each weather station. Third, each RFthermometer 12 transmits redundant temperature and station IDinformation. In one embodiment, five (5) redundant data framesconstitute the data telemetry. Should environmental noise sourcescorrupt part of the telemetry, the multichannel base station 14 would beable to recover any uncorrupted part thereof. Fourth, the multichannelbase station 14 maintains a record of time of receipt for each RFthermometer 12 data transmission and updates temperature data receivedfrom the plural RF thermometers 12 provided the same is received withina predetermined time window. So long as the temperature data from eachchannel (station) is received within the predetermined time window,preferably fifteen (15) minutes in one embodiment and one (1) hour inanother embodiment, from the time of last receipt, the multichannel basestation updates the temperature information it maintains for eachchannel. Otherwise, it provides an indication of an inoperable channel.These channel recovery windows should be sufficient for most noisyenvironments, although a different duration window could be employed.

[0054] Referring now to FIG. 2, generally designated at 40 is anelevational view of the front of one embodiment of the RF thermometer ofthe multi-station RF thermometer and alarm system of the presentinvention. The RF thermometer 40 includes a water-resistant housing 42having O-ring seals, not shown, a well generally designated 44integrally formed in the housing 42 for receiving a temperature probe,and a waterproof temperature probe 46 shown received in the probereceiving well 44. The waterproof probe 46 is connected to the housing42 via an elongated flexible cable 48 of predetermined length,preferably ninety (90) centimeters. A display 50 for displaying thetemperature sensed by the probe 46 is mounted to the housing 42. The RFthermometer 40 is battery-powered, is operational from minus fifty (−50)to plus seventy (+70) Co, has a range of sixty (60) meters obstructed(i.e. through walls), an accuracy of +/− 0.5 Co and a minus forty (−40)to a plus forty (+40)Co range for reliable temperature measurement.

[0055] Referring now to FIG. 3, generally designated at 60 is aperspective view of the back of the portable, battery-powered RFtransmitter of the multi-station RF thermometer and alarm system of thepresent invention with its battery door and wall mounting bracketremoved.

[0056] Chamber generally designated 62 defined in the battery receivingcompartment provides a space in which the cable 48 may be looped andstored between batteries 64. Any selected length of the cable 48 ofpredetermined length may be payed-out of the chamber 42 to allow thewaterproof probe 46 to reach intended temperature measurement locationsas determined by the needs of each particular applications environment.

[0057] As shown, channel “A” and “B” selector and station ID switches66, 68 are preferably mounted in the battery compartment, although anyother suitable location therefor could be employed.

[0058] Referring now to FIG. 4, generally designated at 70 is afunctional block diagram of the portable, battery-powered RF thermometerof the multi-station RF thermometer and alarm system of the presentinvention. Digital controller 72, operatively connected to RAM memoryand ROM memory, not shown, is connected to channel setting and stationidentifying DIP switches 74, temperature sensor 76, LCD display 78, anda three hundred and fifteen (315) megahertz RF oscillator 80. Thechannel set switches 74 preferably are two (2) DIP switches (containingfour (4) SPST switches each), each for channel “A” and for channel “B”.In use, each RF thermometer is set to a different four (4) bit ID codeon either channel, and the receiver is set to either bank A or bank B.This minimizes the problem of interference from a neighboringmulti-station RF thermometer and alarm system, and/or from environmentalsources of interference.

[0059] Although channel selecting and station identifying DIP switchesare presently preferred, other channel setting and/or stationidentifying means in the transmitter could be employed.

[0060] The controller 72 preferably is a OKI Semiconductor MSM64162microcontroller (with internal RAM and ROM). The temperature sensor 76preferably is a Semitec 103AT-2B thermistor. The LCD display 78preferably is a custom-manufactured display.

[0061] The controller 72 (1) measures the resistance of the thermistorof the temperature sensor 76 and numerically calculates the temperaturecorresponding thereto, (2) encodes a data packet having redundant firstdata representative of the sensed temperature and redundant second datarepresentative of the transmitter ID and (3) controls the RF oscillator80 to transmit a data frame having the encoded data packets at randomtime. In addition, the controller 72 performs the functions ofdisplaying the temperature on the liquid crystal display 78 and checkingthe battery voltage.

[0062] In one preferred embodiment, the controller 72 transmits eighthundred eighty five (885) millisecond data packets on a randomizedschedule of approximately twice per minute, randomly selected everythirty (30) to sixty (60) seconds, with no less than thirty secondsbetween transmissions. The average duty cycle of any one hundred (100)millisecond portion of the transmission does not exceed fifty (50)percent, permitting a six (6) dB increase in the peak output power fromthe transmitter. The eight hundred and eighty five (885) millisecondtransmission consists of a preamble followed by five (5) identical dataframes as shown in FIG. 5. A Manchester-like encoding technique ispreferably used for the data frames.

[0063] A preamble signals the start of transmission and allows the dataslicer time to stabilize before the data is sent. Each data framecontains a wait (low) pulse, a sync (high) pulse, a start (low) pulse, asixteen (16) bit channel ID word, a four (4) bit setup word and asixteen (16) bit BCD temperature word.

[0064] The preamble is a square-wave train, consisting of twenty (20)high pulses and nineteen (19) low pulses. The wait pulse is low for two(2) bit periods. The sync pulse is high for four (4) bit periods. Thestart pulse is low for two (2) bit periods. The data is sent as (bit)followed by (complement of bit). Thus, the sixteen (16) bit ID word isrepresented by thirty two (32) bits, the four (4) bit setup word isrepresented by eight (8) bits, and the sixteen (16) bit temperature wordis represented by thirty two (32) bits. The complete transmission isfour hundred and thirty nine (439) bit periods in duration.

[0065] Example of Complete Transmission:

[0066] Channel ID=1101 0011 0101 100=D358

[0067] Temperature=024.7

[0068] (preferably transmitted in oF)=000 0010 0100 0111=0247

[0069] Setup Word=(positive temperature, unused bit, unused bit, batterygood)=1010

[0070] The bits are converted so 0's are represented by 01 and 1's arerepresented by 10. Using this, the data becomes: Channel ID = 1010 01100101 1010 0110 0110 1001 0101 Setup Word = 1001 1001 Temperature = 01010101 0101 1001 0110 0101 0110 1010 Actual Transmission: 1010 1010 10101010 1010 1010 1010 1010 1010 101 preamble 00 wait FRAME 1 1111 sync 00start 1010 0110 0101 1010 0110 0110 1001 0101 channel ID 1001 1001 setupdata 0101 0101 0101 1001 0110 0101 0110 1010 temperature 00 wait FRAME 21111 sync 00 start 1010 0110 0101 1010 0110 0110 1001 0101 channel ID1001 1001 setup data 0101 0101 0101 1001 0110 0101 0110 1010 temperature00 wait FRAME 3 1111 sync 00 start 1010 0110 0101 1010 0110 0110 10010101 channel ID 1001 1001 setup data 0101 0101 0101 1001 01100101 01101010 temperature 00 wait FRAME 4 1111 sync 00 start 1010 0110 0101 10100110 0110 1001 0101 channel ID 1001 1001 setup data 0101 0101 0101 10010110 0101 0110 1010 temperature 00 wait FRAME 5 1111 sync 00 start 10100110 0101 1010 0110 0110 1001 0101 channel ID 1001 1001 setup data 01010101 0101 1001 0110 0101 0110 1010 temperature

[0071] The entire transmission consists of four hundred thirty nine(439) bits in eight hundred eighty five (885) milliseconds, with a bitduration of 2.016 milliseconds.

[0072] In another preferred embodiment, where time-of-next transmissionscheduling is included in the data frames as a means of conserving powerin the multi-station base station, the data frames, in addition to thepreamble, channel ID, and temperature words, include time-to-nexttransmission information. If the “time to next transmission” isrepresented in seconds, six (6) bits will give zero (0) to sixty-three(63) seconds of wait time. Inclusion of these bits (and the complementedbits) adds an additional twelve (12) bits to each frame and sixty (60)bits to the complete packet, giving a four hundred ninety nine (499) bittransmission. An alternative means of specifying the “time to nexttransmission” is to send the number of seconds deviation from theaverage transmission interval. For instance, if the transmissionrandomly deviates by plus/minus ten (10) seconds from a nominal value offorty (40) seconds, a five (5) bit time code could be used (range 00-31seconds or plus/minus 16 seconds). If it is desired to have a muchlonger interval between transmissions, the actual time and date of thenext transmission(s) could be set. This could be represented in BCDdigits in seconds/hr/days/month format, or by a count-down timeexpressed in seconds (or tens of seconds, or hundreds of seconds, and soon.) Other schemes may be employed as well without departing from theinventive concepts.

[0073] Referring now to FIG. 6, generally designated at 100 is aschematic circuit diagram of the RF oscillator of the portable,battery-powered RF transmitter of FIG. 4. The RF oscillator includestransistor Q1 in a saturated Pierce-like oscillator configuration,preferably resonant at three hundred and fifteen (315) megahertz, withfrequency stabilized by SAW resonator marked “SAW1 ” connected to thebase of transistor Q1. A loop antenna marked “LOOP ANT” is preferablyetched with the oscillator on a printed circuit board, not shown. ON/OFFkeying (“OOK”) modulation of the three hundred and fifteen (315)megahertz carrier is provided for by applying zero (0) and positivethree (+3) volt logic levels to the data input (resistor R3) from thecontroller 72 (FIG. 4). Elements R1, R2, R3, R4 and R5 set the operatingpoint of transistor Q1; (R3 also serves as an input port for modulatingthe transmitter), elements C4, C5 and C6 in conjunction with the loopantenna provide a tuned output network that attenuates harmonics. C3 isa bypass capacitor to prevent RF energy being fed back to the controllerthrough the data input . Element C1 is a bypass capacitor to provide alow impedance path for the circulation of RF current. C2 couples theoutput network to the collector of Q1. L1 is the collector inductor.

[0074] Referring now to FIG. 7, generally designated at 110 is a flowchart illustrating the operation of the controller of the portable,battery-powered RF thermometer of the multi-station RF thermometer andalarm system of the present invention.

[0075] As shown by a block 112, the processor is operative toinitialize, and as shown by a block 114, is operative to determinewhether five (5) seconds have elapsed.

[0076] If five (5) seconds have elapsed, the processor is operative tocheck channel identification and battery status as shown by a block 116.Although the processor preferably checks channel ID and battery statusevery five (5) seconds, other intervals could be employed.

[0077] As shown by a block 118, the processor is then operative todetermine whether it is time to randomly transmit its data packet ofredundant data frames. Any suitable technique, such as a random numbergenerating algorithm, may be employed.

[0078] If it is, and time-of-next transmission scheduling is employed,the processor is operative to generate a schedule of random transmissiontimes as shown by a block 120, and then is operative to transmit itsdata packets as shown by a block 122.

[0079] As shown by a block 124, the processor is then operative todetermine if thirty (30) seconds have elapsed since the last temperaturemeasurement. If thirty (30) seconds have not elapsed, processing returnsto the block 114. Although thirty (30) second temperature measurementintervals are presently preferred, other temperature measurementintervals could be employed.

[0080] As shown by a block 126, if thirty (30) seconds have elapsed, theprocessor is operative to measure the temperature, and processingreturns to the block 114.

[0081] Referring now to FIG. 8, generally designated at 130 is a frontelevational view of one embodiment of the multichannel base station ofthe multi-station RF thermometer and alarm system of the presentinvention. The multichannel base station 130 includes a housing 132, aneasy-to-read multi-field reconfigurable display 134 mounted to thehousing 132, a scroll key 136, a control panel schematically illustratedby bracket designated 138 and a control panel door 140 that protects thecontrol panel 138 when it is not being used. The base station 130includes one (1), two (2) position channel switch, a piezo audiblealerter and an audible alerter disable switch, not shown. Although achannel setting DIP switch is presently preferred, other channel settingmeans in the receiver could be employed.

[0082] The control panel 138 includes three (3) alarm keys 142, 144, and146 respectively marked “set min”, “set max”, and “done on/off”; a“low/high” “when?” key 148; a “oC/F” key 150; an hour set key 152 marked“hour”; a minute set key 154 marked “minute”; a “12/24” key 156; a monthkey 158 marked “month”; a day key 160 marked “day” and a year key 162marked “year”.

[0083] The multichannel base station 130 is operable in three (3) basicmodes. In a decode/display mode described more fully hereinbelow, themultichannel base station 130 concurrently displays temperatureinformation for each active location (remote and base), as well asdisplays temperature high and low information for any location selectedby depressing the scroll key 136.

[0084] In alarm set mode described more fully hereinbelow, themultichannel base station 130 allows the user to independently set alarmminimum and maximum temperature limits for each temperature location byuse of the scroll key 136 and the set min, set max, and on/off keys 142,144, 146.

[0085] In alarm announce mode described more fully hereinbelow, themultichannel base station 130 provides audible, visible and/or remotesignal indications whenever one or more monitored locations havetemperature values that are out-of-bounds.

[0086] The C/F key 150 changes the display from centigrade to Fahrenheitin any mode.

[0087] The low/high when? key 148, when depressed, displays the high andlow temperatures for locations selected by the scroll key 136, as wellas the time when those highs and lows were registered.

[0088] The hour, minute and 12/24 keys 152, 154, and 156 set the time;and the month, day, and year keys 158, 160, and 162 set the date.

[0089] Description labels, not shown, may be provided on the inside ofthe door 140 to identify the locations of each of the one or more remoteRF thermometers.

[0090] Referring now to FIG. 9, generally designated at 190 is afunctional block diagram of the multichannel base station of themulti-station RF thermometer and alarm system of the present invention.

[0091] A digital controller 192, preferably a Samsung KS57C2616microcontroller with internal ROM and RAM, is connected to a localtemperature sensor 194 (preferably consisting of a OKI SemiconductorMSM64162 microcontroller and Semitec 103AT-2B thermistor), a receiver196, a multi-field re-configurable display 198, control panel 200,channel set switches 202 and to visible and audible alarms respectivelydesignated 204, 206.

[0092] The local temperature sensor 194 preferably includes a thermistorlocated in the base station operative to sense the temperature in theenviron thereof. Preferably, the local temperature sensor 194 includes amicrocontroller, not shown, which measures the local temperature andsends this to the digital controller 192 which processes and displaysthe data on the display 198 in a manner to be described.

[0093] In one preferred embodiment, the digital controller 192 processesdata received by the receiver 196 and displays data on the display 198from up to four (4) remote temperature sensors, although a differentnumber of remote temperature sensors could be employed. The controller192 also monitors the keypad 200, keeps track of the time and date, andchecks for alarm conditions (temperature exceeding user-specified limitsat any location). In one embodiment, power is supplied by an externalvoltage adapter, and the multi-station base station is always “on.” Inanother embodiment, where time-to-next-transmission data is provided,the multi-station base station is battery powered, waking-up to receivetransmissions at scheduled times out of “sleep” mode. A battery backupcircuit maintains the clock and user settings in event of power failureor power down. The visible alarm 204, preferably an LED, and the audiblealarm 206, preferably a piezoelectric beeper, indicate the presence ofan alarm condition.

[0094] Referring now to FIG. 10, generally designated at 220 is aschematic circuit diagram of the receiver 196 (FIG. 9) of themultichannel base station of the multi-station RF thermometer and alarmsystem of the present invention. The receiver 220 includes a tunedcircuit illustrated by dashed box 222 that improves selectivity.Capacitors C11, C13, C15 and inductors L2, L3 preferably are tuned tothree hundred and fifteen (315) megahertz.

[0095] An input buffer schematically illustrated by dashed box 224 thatminimizes radiation from the antenna is connected to tuned circuit 222.Buffer 224 includes transistor amplifier Q3.

[0096] Capacitors C12, C14 couple the input signal to the base oftransistor Q3, while resistors R6, R10 and R14 bias transistor Q3 tooperate in a linear manner. R6 also serves as a collector loadresistance. Capacitor C4 is a power supply decoupling capacitor.

[0097] A demodulator schematically illustrated by dashed box 226 fordetecting the received signal is connected to transistor Q3 of the inputbuffer 222 via coupling capacitor C8. The demodulator includestransistor Q2 operated as a super-regenerative detector. Resistors R3,R4, R13 and R18 define the operating point of transistor Q2. CapacitorsC7, C1S and resistors R4, R18 form the quench network for thesuper-regenerative detector. Inductor L4 serves to isolate the signalvoltage from the biasing network. Resistor R15 and capacitor C19 providea low-pass filter to remove quench-frequency components from thedetector output, while the filtered output is coupled to the data slicerinput via capacitor C17. Capacitor C1 provides power supply decoupling.Inductor L1 in conjunction with capacitors C5 and C10 form a tankcircuit tuned to resonate at three hundred and fifteen (315) megahertz.

[0098] Data slicer schematically illustrated by dashed box 228 forextracting digital data from the detected signal is connected to thedetector 226. The data slicer looks at the detector output, and respondsto variations about the average signal level, corresponding to thedigital data stream. Operational amplifier marked “U2A” is configured asa non-inverting amplifier to boost the detected signal. Operationalamplifier marked “U2B” is configured as a comparator with hysteresis(Schmitt trigger circuit). Resistors R1 and R8 and capacitor C17 couplethe demodulated signal to U2A while providing a high-pass filter toremove DC and slowly varying AC components. Resistors R5 and R9 set thegain of U2A. Resistors R1 and R2 provide a reference voltage to thenon-inverting input of U2A. Capacitor C18 provides power supplydecoupling. Capacitor C9 and resistor R11 low-pass filter the signalgoing to the inverting input of U2B. Resistors R16 and R17 set theamount of hysteresis. Resistor R16 also couples the U2A output to theU2B non-inverting input.

[0099] A level translator schematically illustrated by dashed box 230 isconnected to the data slicer 228. With the RF carrier ON, the dataoutput is approximately 0.2 volts; with the RF carrier OFF, the dataoutput is positive five (+5) volts. Transistor Q1 is a clippingamplifier. Resistor R12 couples the data slicer output to the base ofQ1. Resistor R7 is the collector resistor. Capacitor C20 prevents RFenergy from the digital board from being fed back to the receiverthrough the data output. Capacitor C6 is a power supply bypasscapacitor.

[0100] Referring now to FIG. 11, generally designated at 240 is a statediagram of the controller 192 (FIG. 9) of the multichannel base stationof the multi-station RF thermometer and alarm system of the presentinvention. As shown by a block 242, the processor is operative in adecode/temperature display mode; as shown by a block 244, is operativein an alarm set mode; and as shown by a block 246 is operative in analarm announce mode. As shown by an arrow marked “min, max, done”extending between the decode/temperature display mode 242 and the alarmset mode 244, the processor transitions from mode 242 to mode 244whenever the user presses the min, the max, or the done key 142, 144, or146 (FIG. 8).

[0101] As shown by an arrow marked “on/off, 20 sec's” extending betweenalarm set mode 244 and decode/temperature display mode 242, theprocessor is operative to transition from the alarm set mode back to thedecode/temperature display mode whenever the operator depresses the doneon/off key 146 (FIG. 8), or when twenty (20) seconds of inactivity haveelapsed.

[0102] Whenever an out-of-bounds alarm condition exists at any of theremote and/or base locations, the processor is operative to transitionfrom the temperature display mode 242 to the alarm announce mode 246 asillustrated by an arrow 252 marked “alarm condition.”

[0103] As illustrated by an arrow marked “on/off” extending from thealarm announce mode 246 the decode/temperature display mode 242, theprocessor is operative to transition from the alarm display mode to thedecode/temperature display mode whenever the operator pushes the done,on/off key 146 (FIG. 8).

[0104] As illustrated by an arrow marked “min, max” extending betweenthe alarm announce mode 246 and the alarm set mode 244, the processor isoperative to transition from the alarm announce mode to the alarm setmode whenever the operator depresses the min key 142, or the max key 144(FIG. 8).

[0105] With reference now to FIG. 12, which shows a pictorial diagramgenerally designated 270 that illustrates the display of the multi-fieldre-configurable display configured in decode/display mode, the operationof the multi-channel base station in decode/display mode will now bedescribed. In decode/display mode, the display includes acomparatively-large active location field 270 and five (5)comparatively-smaller temperature station (remote and base) fieldsgenerally designated 272. Each of the five (5) temperature stationfields 272 includes a temperature field 274, an alarm set field 276, anda station ID field 278.

[0106] A daily low icon field 280, a daily low temperature field 282, adaily high icon field 284, and a daily high temperature field 286 areprovided below the active location field 270. Degree centigrade anddegree Fahrenheit fields 288, 290 are provided immediately to the rightof the active location field 270.

[0107] Time field 292, and a date field 294, are provided adjacent thebottom of the display.

[0108] Upon startup, the initial display is called the “idle” displaywhich shows all temperatures for all active locations (base and remote)in the five (5) temperature station fields 272, and displays the basestation temperature in the active location field 270. Each location isnumbered “1”, “2 ”, “3”, “4”, and “base” in the station identificationfields 278. Only locations that have active data are displayed. Allother locations remain blank, including their location number. Allalarms are initially off. Default is degrees Fahrenheit.

[0109] A circle, not shown, around the location number is displayed inthe station identification field 276 to indicate the active location.

[0110] The lowest and highest registered temperature in the past twentyfour (24) hours (preferably reset at midnight each day) is displayed inthe low and high temperature fields 282, 286 below the active largereadout temperature field 270, and high and low icons are displayed inthe low and high icon fields 280, 284. The temperature display for alllocations is oF/oC switchable by depressing the oC/F key 150 (FIG. 8),and the corresponding icon is displayed in the centigrade and Fahrenheiticon fields 288, 290.

[0111] If a good signal has not been received from a remote transmitterin a fifteen (15) minute period, abad signal screen indicator(preferably, “Blank”) is displayed in that temperature location field274. If the faulty location is the active location, then both the largedisplay readout 270 and the smaller temperature display 272 are blanked.

[0112] For the eleven (11) keys of the control panel 138 (FIG. 8)accessed by opening the door 140 (FIG. 8) on the front of the unit,pressing a key once gets you into its function and pressing it againtakes you back out of the function to idle screen. The exception is for“set min” and “set max” keys 142, 144 (FIG. 8); the “alarm on/off/done”key 146 (FIG. 8) needs pressed to exit.

[0113] When in a set up mode (time, date, alarm), if no keys are pressedfor twenty (20) seconds, then the display returns to the idle displayand any changes made by the operator inside any function are saved. Theexception is exiting in “alarm announce” mode, either by pressing thedone/on/off key 146 (FIG. 8) or by pressing the min or max keys 142, 144(FIG. 8).

[0114] The “C/F” key 150 and the “12/24” key 156 (FIG. 8) alternatebetween their two modes each time the key is pressed.

[0115] From idle display, the “low/high/when?” button 148 (FIG. 8) whenpressed flashes the daily low icon in the daily low icon field 280 whileit shows the active location temperature and the hours/minutes when thisdaily low temperature was recorded. After five (5) seconds, the displayflashes “daily high” for five (5) seconds in the daily high icon field284 and shows temperature and time of day when the daily high wasreached, then returns to idle display.

[0116] The sound on/off slide switch, on the side of the unit, notshown, controls the piezoalerter 206 (FIG. 9). In the “off” state allsounds including the key click sound is turned off.

[0117] Whenever a user presses an incorrect key a negative (5) quickbeeps sound is heard and no changes are made.

[0118] When in time change mode, if the “12/24” key 156 (FIG. 8) ispressed, then it toggles and leaves time change mode, saves any changesmade, and returns to the idle screen.

[0119] When in any set mode, if the receiver receives data from atransmitter it saves it and updates the display only after the operatorexits from the set mode.

[0120] With reference now to FIG. 13, which shows a pictorial diagramgenerally designated 300 of the multi-field re-configurable displayconfigured in “alarm set” mode, the operation of the processor in alarmset mode will now be described. The set alarms display 300 is generallythe same as the idle display of FIG. 12, except that the daily high andlow icon and temperature fields are reconfigured to display minimum andmaximum icons 302, 304 and minimum and maximum value fields 306, 308;and except that a “set temperature” icon field 310 is provided.

[0121] When a user presses the “set min” or “set max” buttons 142, 144(FIG. 8), the display changes from the idle display to the “set alarms”display. In the set alarms display, the active location is the onlytemperature shown (in the lower temperature area 272 and in the largerupper display area 270). The daily high/low values disappear, and arereplaced by the min and max alarm range temperature values in the minand max value fields 306, 308. When the current temperature locationgoes outside these values, then the alarm mode to be described for thislocation becomes active.

[0122] Alarm min/max values are set one location at a time. The firsttime the “set min” or “set max” buttons 142, 144 (FIG. 8) are pressed,the “min” number shows five (5) degrees below the current temperature ofthat location and the “max” value starts at five (5) degrees above thecurrent temperature in the min and max value fields 306, 308. Afterthis, when entering new set min and set max values, the values will bethe previously set values.

[0123] To set the minimum and maximum temperature targets for alocation, the scroll bar 136 (FIG. 8) is depressed to select thelocation to set. In the set alarms display mode, the active location isthe only temperature shown in the temperature station fields 272 and inthe active location field 270.

[0124] The set min key 142 (FIG. 8) is depressed once. The words “setmin” start flashing in the minimum field 302 and “set temperature alarm”is displayed in the set temperature icon field 310.

[0125] The scroll bar 136 (FIG. 8) is then depressed to adjust thetemperature limit up or down until the desired number is reached.Adjustment occurs one-tenth (0.1) degrees at a time at a rate of two(2.0) degrees per second. When in alarm min/max set mode, the scrollrate goes to five (5) degrees/second if the scroll key 136 (FIG. 8) isheld for more than three (3) seconds.

[0126] In a similar manner, the set max key 144 is depressed and thescroll bar 136 (FIG. 8) is then depressed to adjust the maximumtemperature as well, whereupon the set max words start flashing in themax icon field 304.

[0127] To exit alarm set mode, the done key 146 (FIG. 8) is depressed.The alarm mode is automatically switched to “on” upon exit. An iconappears in the alarm set field 276 beside the location number in thestation identification field 278 to indicate that this location is nowin the “on” state. At the top the display, the daily low and hightemperatures being displayed for that location are replaced with the minand max set temperatures for that location while the alarm is in the“on” condition.

[0128] When in the alarm set mode the minimum temperature cannot goabove the maximum temperature and the maximum temperature cannot gobelow the minimum. A beep is heard if min and max become equal.

[0129] With reference now to FIG. 14, which shows a pictorial diagramgenerally designated 330 of the multi-field re-configurable displayconfigured in alarm announce mode, the operation of the processor inalarm announce mode will now be described. The alarm announce modedisplay 330 is generally the same as the alarm set display 300 (FIG.13), except that the set temperature icon field is reconfigured as atemperature alarm icon field 332, and an LED alarm 334 and an audiblealarm, not shown, are enabled.

[0130] If the temperature of any location goes outside the min-max alarmrange and the alarm for that location has been turned on (icon displayedin the alarm set field 276 beside the location identifier in the stationidentification field 278), then an alarm announce state exists and thedisplay goes into the “alarm announce” display mode. The location withthe alarm becomes the active location and is the only location thatshows on the display (in the lower 272 and upper 270 display areas). The“temperature alarm” icon is displayed in the temperature alarm iconfield 332, and it flashes. The LED 334 flashes, the “alarm on” icon inthe temperature alarm icon field 332 flashes, and if sound is “on”, thesound beeps.

[0131] To exit the alarm announce state, the operator can do severalthings. (All keys except min, max, and done are locked out and cannot beused). The operator can press the alarm on/off button 146 (FIG. 8) whichturns the alarm on/off icon off and, after one (1) seconds, the displayreturns to idle mode display. The operator could also press either the“set min” or “set max” buttons 142, 144 (FIG. 8) and the displayimmediately goes to the “set alarms” display mode and the operator mayadjust the min-max range to turn off the alarm in the manner describedabove. If the operator leaves the “set alarm” mode and an alarmcondition still exists, then the display returns to the idle display forone (1) second, then returns to the “alarm announce” display.

[0132] When a multiple alarm condition exists, then the “alarm announce”display shows all locations in the temperature station fields 272 thathave an alarm condition. The “active” location is the location with thelowest number (e.g., “1” instead of “3”, or “2” instead of “3”, etc.;“base” location is location “0”). The operator depresses the scroll key136 (FIG. 8) to handle each alarm state, one location at a time, in themanner described above. When an alarm is cleared, then after one (1)second, that location disappears from the display and the next lowestnumber location become the “active” location. When the last location iscleared, then the display waits two (2) seconds and returns to idledisplay.

[0133] If a good signal has not been received from a remote transmitterin a fifteen (15) minute period, that temperature location goes blank,indicating a bad transmission. If the faulty location is the activelocation, then both the large display read out and the smallertemperature display with the location number defaults to the base as theactive location.

[0134] Referring now to FIG. 15, generally designated at 350 is a flowchart of the processor of the multi-channel base station of themulti-station RF thermometer and alarm system of the present invention.As shown by a block 352, the processor is operative to determine if anytemperature data is available. In one embodiment, the processor isalways on, monitoring for temperature data. In another, it is “asleep,”waking up at scheduled times to monitor for temperature data. Anysuitable data monitoring technique, such as an interrupt, may beemployed.

[0135] If data is available, the processor is operative to determinewhether two (2) frames of the redundantly transmitted data match asshown by a block 354.

[0136] As shown by a block 356, if two (2) frames match, the processoris operative to update the system data. System data includes the time oflast receipt and the minimum and maximum received temperature valuesreceived in a twenty four hour period.

[0137] As shown by a block 358, the processor is then operative todetermine whether the received temperature data is out of bounds.

[0138] If it is, as shown by a block 360, the processor is operative toupdate the display, and to transition to alarm mode as shown by a block362.

[0139] If no temperature data is available, or if two (2) frames of theredundantly transmitted data do not match for a given channel, or ifthere is no out of bounds conditions, the processor is operative todetermine whether there has been a key press as shown by a block 364.

[0140] If there was a key press on the control panel, the processor isoperative to handle the key press as shown by a block 366 and to updatesystem data as appropriate.

[0141] As shown by a block 368, if the keypress input changed operatingmode, the processor is operative to transition to alarm set mode asshown by a block 368.

[0142] As shown by a block 370, the processor is then operative todetermine whether any data is older than fifteen (15) minutes since thelast temperature data was received.

[0143] If it is, the processor is operative to blank the record as shownby a block 372.

[0144] As shown by a block 374, the processor is then operative toupdate the display, and processing returns to the block 352.

[0145] Referring now to FIG. 16, generally designated at 400 is anelevational view of the front of another embodiment of the RF weatherstation of the multi-station RF thermometer and alarm system of thepresent invention. The RF weather station 400 includes a water-resistanthousing 402, a first weather parameter sensing probe connected to thehousing 402 via an elongated flexible waterproof cable that sensestemperature, not shown, a second weather parameter sensing probe withinhousing 402 that senses percent relative humidity, not shown, and adisplay 404. Like the embodiment described above in connection with thedescription of FIGS. 2 and 3, a chamber, not shown, is provided in thehousing 402 in which the cable of the temperature probe may be stowedand payed-out to allow the probe to reach intended temperaturemeasurement locations as determined by the needs of each particularapplications environment. A weather station location identificationswitch, preferably a sequential select switch, not shown, is mounted tothe housing 402 to allow user selection of weather station locationnumber, and a Centigrade/Fahrenheit switch, not shown, is mounted to thehousing 402 to allow user selection of temperature scales. The display404 displays the temperature sensed by the selectably extendable firstprobe mounted to the housing, and displays indicia representative of theselected weather station location number, and of the temperature scaleselected. The display 404 also displays indicia representative that adata packet to be described is being telemetered.

[0146] The RF weather station 400 is battery-powered, is operationalfrom minus forty (40) degrees Fahrenheit to one hundred twenty-two (122)degrees Fahrenheit, and has a range of up to about two hundred fifty(250) feet.

[0147] Referring now to FIG. 17, generally designated at 420 is afunctional block diagram of the portable, battery-powered RF weatherstation of the multi-station RF thermometer and alarm system of thepresent invention. Digital controller 422, operatively connected to RAMmemory 424 and ROM memory 426, is connected to sequential-select stationidentifying switch 428 (and Centigrade/Fahrenheit scale select switch),temperature sensor 430, humidity sensor 432, LCD display 434, and to thethree hundred fifteen (315) MHZ oscillator 436 described above inconnection with the description of FIGS. 4 and 6, not separatelydescribed again for the sake of brevity of explication. In use, each RFweather station is set to a different station identification number bythe sequential-select station identifying switch 428. The ROM 426includes plural unique transmission schedules to be described, anotherone of which is selected for each setting of the sequential-selectstation identification switch 428. For the three (3) stationidentification switch settings of the preferred embodiment, another oneof three (3) unique transmission schedules, preferably {60 seconds +/− 1second}, {60 seconds +/− 5 seconds}, and {60 seconds +/− 10 seconds}, isselected. For example, location “3” will transmit repetitivelyalternately at fifty (50) seconds and seventy (70) seconds. Althoughtwo-phase repeat schedules are presently preferred, more than two (2)phase schedules, one-time phase offsets at the time of start-up topromote substantially contention-free reception, or other uniqueschedules to substantially preclude contention-induced interference atthe receiver and to allow the receiver to enter low-power mode until thetime of next transmission, could be employed without departing from theinventive concepts.

[0148] The controller 422 preferably is the OKI Semiconductor MSM64162.The temperature sensor 430 preferably is the Semitec 103AT-2Bthermistor. The humidity sensor preferably is the Shinyei Kaisha C5-M3humidity sensor. The LCD display 434 preferably is a custom-manufactureddisplay.

[0149] The controller 422 (1) measures the resistance of the thermistorof the temperature sensor 430 and numerically calculates the temperaturecorresponding thereto, (2) measures the resistance of the humiditysensor 432 and calculates the humidity corresponding thereto, (3)encodes a data packet having first data representative of data type,weather station ID and phase of the two-phase transmission schedule, andredundant second data representative of weather parameter sensed, and(4) controls the RF oscillator 436 to transmit the data frame having theencoded data packets at preselected times. In the preferred embodiment,the controller 422 alternatively transmits temperature data and humiditydata in sequential data packets, although any other method may beselected for telemetry of multiple weather parameter data. Thecontroller 422 performs the functions of displaying the temperature onthe liquid crystal display 434 and the indicia representative of stationidentification, active transmission, temperature scale selected, as wellas checks the battery voltage.

[0150] In the preferred embodiment, the controller 422 transmits inaccord with the particular unique transmission schedule selectedapproximately once per minute. The average duty cycle of anytransmission does not exceed twenty-five (25) percent, permitting atwelve (12) dB increase in the peak output power from the transmitter.The transmission consists of a preamble, a sync word, and a setup wordfollowed by two identical data frames, as shown in FIG. 18.

[0151] A modified Manchester-like encoding technique that maximizesreceiver sensitivity and provides higher output peak power than theembodiment of FIGS. 2-7 is preferably used for the entire transmission,where a “1” is represented by the pulse sequence “1000” and a “0” isrepresented by the pulse sequence “0100.” The “1” in each pulse sequenceindicates the transmitter is pulsed on for four and one-half (4.5)milliseconds, while the “O” indicates that the transmitter is turned offfor four and one-half (4.5) milliseconds. This coding technique inaccord with the present invention provides the twenty-five (25) percentduty cycle, and its accompanying improvement in higher output peakpower, and also insures that the transmitter cannot be on for more thanone (1) consecutive four and one-half (4.5) millisecond interval, whichhelps to maximize receiver sensitivity by minimizing “ripple” in thedata slicer circuit.

[0152] For example, if a digital “7” is to be sent, which is “0111” instandard BCD representation, it first is transformed in accord with themodified Manchester encoding technique of the present invention, andtransmitted as “0100 1000 1000 1000. ” It takes sixteen (16) pulsesinstead of four (4) bits as a bit is represented by four (4) pulses.Since there are only four (4) high pulses (1's) and twelve (12) lowpulses (0's), the average energy output is twenty-five (25) percent “on”and seventy-five (75) percent “off.” When data is joined, two “1's” arenever present side-by-side as a zero (0) is always at least at one end.This maximizes receiver sensitivity. High pulses butted together becomea single double-duration pulse, which has the undesirable effect ofincreasing voltage ripple in the data slicer, thus degrading itssensitivity. This undesirable effect is overcome by the encodingtechnique of the present invention, which makes the data look as much aspossible like a continuous stream of “1000 1000 1000 1000 1000 . . . ”

[0153] The preamble is a string of “1000 1000 1000 . . . ” followed bythe sync pulse which is two (2) high periods in length. The redundantlyencoded weather data immediately follows.

[0154] Example of Complete Transmission: DATA STREAM: PREAMBLE SYNCSETUP DATA FRAME1 (fixed pattern) (wide pulse) (xxx) (yyyy)humidity/temp. phase battery low DATA FRAME2 (zzzz) example:1000100010001 00011000 100001001000 PREAMBLE SYNC encoded “ 101” SETUPDATA 0100010001000100/0100100010000100/0100100001001000/000010010001000DATA FRAME 1 encoded “0000” “0110” “0101” “0011”  0  6  5  3 (encoded65.3 C. temperature)0100010001000100/0100100010000100/0100100001001000/000010010001000 DATAFRAME2

[0155] Data frame2 is identical to data frame1.

[0156] Referring now to FIG. 19, generally designated at 440 is a flowchart illustrating the operation of the controller of the portable,battery-powered RF weather station of the multi-station RF thermometerand alarm system of the present invention.

[0157] A shown by block 442, the processor is operative to initializeand to determine the number and kind of weather parameter sensors andthe station identification number.

[0158] A shown by block 444, the processor is operative to measure thevalue of the active sensors. In the preferred embodiment, wheretemperature and humidity sensors are present, the processor isalternatively operative to measure temperature and humidity preferablyevery five (5) seconds.

[0159] As shown by block 446, the processor is operative to convertmeasured sensor data to a corresponding temperature and/or humidityweather parameter. Preferably, the processor of the transmitter of eachbattery-powered weather station computes the relevant weather parameter,thereby off-loading that task away from the processor of the receiver,although unconverted sensor data could be transmitted.

[0160] As shown by block 448, the processor is operative to display thecurrent temperature data and the location identification number.

[0161] As shown by block 450, the processor is then operative todetermine the time-to-next transmission and waits until that time asshown by block 452.

[0162] As shown by block 454, the processor then transmits the encodeddata packet at the prescheduled time, and processing returns to block444.

[0163] Referring now to FIG. 20A, generally designated at 460 is a frontelevational view of another embodiment of the multichannel base stationof the multi-station RF thermometer and alarm system of the presentinvention. The multichannel base station 460 includes a housing 462, aneasy-to-read multi-field re-configurable display 464 mounted to housing462, a scroll-up and scroll-down key 466, a daily high/low andtemperature alarm setting key 468, and a reset/heat index key 470. Thedisplay 464 includes a comparatively-large, upper portion and acomparatively-smaller, lower portion. The enlarged display portion showsthe temperature of a selected active location, (or selectably its heatindex if that location monitors both temperature and humidity), and thesmaller display portion simultaneously shows for each of the remoteweather stations and the base station as identified by the illustrated“1,” “2,” “3,” and “base”indicia the current temperatures (or percentrelative humidity, for location(s) that monitor both temperature andhumidity, as indicated by the icon “% ” for location “2” in FIGS. 20A,B). An indication as shown by the “triangle” icon above location “2” isprovided as to which location is currently selected for display in theupper portion. Depression of the scroll key 466 selects an activelocation for display in the upper portion of the display 464, as shownin FIG. 20B, and depression of the daily high/low and alarm setting key468 displays daily low, daily high, alarm min, and alarm max for anyselected active location in the lower portion of the display 464, asshown in FIG. 20C. Depression of the reset/heat index key 470 displaysthe numeric value of the heat index in the upper portion of the display464 for a selected active location and the indicia “heat index,” notshown, and depression of the reset/heat index key 470 followingdepression of the daily high/low and alarm setting key 468 resets theperiod during which the daily high and daily low values are recorded. Atemperature alarm “on” indicator illustrated by a “bell” icon in theupper left corner of the display 464 indicates temperature alarm “armed”status. Below that, a radio transmission indicator illustrated by icon“(.)” and a temperature trend indicator illustrated by the upwardlydirected “arrow” in the upper portion of the display 464 respectivelyindicate when telemetry is being received and the direction and speed oftemperature change of any active location selected. A flashing “bell”icon is shown in the lower portion of the display 464 for any activelocation that has an out-of-bounds alarm condition. A low batteryindicator and a temperature alarm LED, both not shown, respectivelyprovide an indication of low battery power and a visible indication ofan out-of-bounds alarm condition. A piezoalerter, not shown, provides anaudible indication of an out-of-bounds alarm condition. A temperaturescale selector switch, an alarm on/off key, and a sync key, all notshown, are respectively provided to select temperature scale, turn alarmmode on/off, and initiate sync mode whenever, for example, new remoteweather stations are added or it is otherwise desirable to(re)acquireremote weather station's telemetry. Opposite the “bell” icon, indicia,such as the illustrated “F, ” shows the temperature scale selected.

[0164] Referring now to FIG. 21, generally designated at 480 is afunctional block diagram of the multichannel base station of themulti-station RF thermometer and alarm system of the present invention.

[0165] A digital controller 482, preferably a Samsung KS57C2308/16microcontroller with internal ROM and RAM, is connected to a localtemperature sensor 484 (preferably consisting of the OKI SemiconductorMSM64162 microcontroller and the Semitec 103 AT-2B thermistor), thereceiver 486 (described above in connection with the description of FIG.10, not separately described again for the sake of brevity ofexplication), multi-field re-configurable display 488, keypad 490, andto visible and audible alarms respectively designated 492, 494. Thecontroller 482 is battery-powered, and turns the receiver 486 “on” and“off” at times scheduled to receive transmissions from active locationsas determined by reception clocks 496. For the presently preferredembodiment that monitors telemetry from three (3) remote weatherstations of the type described above in connection with the descriptionof FIGS. 16-19, three (3) reception clocks are maintained, but adifferent number could be employed in accord with the present invention.

[0166] Referring now to FIG. 22, generally designated at 500 is a statediagram of the controller 482 (FIG. 21) of the multichannel base stationof the multi-station RF thermometer and alarm system of the presentinvention. As shown by a block 502, the processor is operative in adecode/display mode; and as shown by a block 504, is operative in analarm set mode.

[0167] In decode/display mode, the controller is operative to identifywhich remote locations are active and to set the reception clocks 496(FIG. 21) for each location identified as active.

[0168] Once active locations are acquired, the controller powers-downthe receiver 486 (FIG. 21) except at times when transmissions arescheduled, which conserves battery power and provides long-lifeoperation. When transmissions are scheduled, the controller powers-upthe receiver 486 (FIG. 21), decodes received data packets, and updatesthe display when received telemetry is in proper format and theredundantly transmitted data frames match. It powers-down the receiverthereafter, or if there is no data frame match, or if the data format isimproper. It lowers its clock speed when it powers-down the receiver,also to conserve battery power and improve useful battery life; viceversa, it raises its clock speed when transmissions are expected. Thecontroller in decode/display mode handles key presses; monitors anddisplays temperature trends; maintains a record, and selectablydisplays, the daily high and low values for active locations; monitorsand displays out-of-bounds alarm conditions; selectably displays theheat index; as well as provides the other audible and visible indicatorsdescribed above in connection with the description of FIG. 20.

[0169] When a temperature alarm sounds in decode/display mode, there aretwo (2) ways to turn the alarm “off. ” Either the alarm on/off button isdepressed to turn the alarm function “off” for all active locations, orthe active alarm location is selected and the daily temperature/alarmset button is depressed to reset the alarm bounds in alarm set mode tobe described.

[0170] Whenever the heat index key is depressed in decode/display mode,the controller is operative to calculate and display heat index for theactive location selected. Heat index is a more accurate measurement ofcomfort than temperature alone, i.e., it provides “apparent temperature,” what the temperature really feels like. It not only is a usefulcomfort indicator, but it may prove invaluable in times when temperatureand humidity can lead to dangerous heatstroke levels. For example, witha temperature of one hundred (100) degrees Fahrenheit and a relativehumidity of sixty (60) percent, the temperature will actually feel likeone hundred thirty (130) degrees Fahrenheit. Preferably, the followingalgorithm is used to calculate heat index. HI=−42.379+(2.04901523*T)−(0.22475541*T*H)−(0.00683783*T*T)−(0.05481717*H*H)+(0.00122874*T*H)+(0.00085282*T*H*H)−(0.00000199*T*T*H*H), where “HI” is heat index,“T” is temperature in degrees Fahrenheit and “H” is percent relativehumidity.

[0171] Although heat index could be calculated for each combination ofhumidity and temperature, it is preferred that a look-up data table, notshown, be employed for this purpose.

[0172] As shown by an arrow marked “alarm ‘on/off’” extending betweenthe decode/display mode 502 and the alarm set mode 504, the processortransitions from mode 502 to mode 504 whenever the user presses thealarm “on/off” key. To set or reset temperature alarm limits in alarmset mode upon depression of the alarm on/off button, the scroll key isdepressed to select an active location for which alarm limits are to beset. The daily temperature/alarm set button is depressed to displaydaily high/daily low temperatures and temperature alarm lower and upperlimits in the lower portion of the display 464 (FIG. 20); the alarm minicon will flash showing it is in “set” mode. The scroll keys aredepressed to adjust the lower temperature alarm limit. After that hasbeen set, depression again of the daily temperature/alarm set buttonaccepts the lower range limit, and the alarm max field icon will thenstart flashing. The scroll keys are again depressed to adjust the uppertemperature limit. Depression of the daily temperature/alarm set buttonaccepts that value, and as shown by the arrow extending from the alarmset mode 504 to the decode/display mode 502, the controller returns tothe decode/display mode 502.

[0173] Referring now to FIG. 23, generally designated at 510 is aflowchart of the processor of the multi-channel base station of themulti-station RF thermometer and alarm system of the present invention.As shown by block 512, the processor is operative to identify activelocations, set the reception clocks for each active location identified,and to extract valid weather data. As shown by block 514, the processorthen displays the temperature and/or humidity weather data recovered foreach active location on the display.

[0174] A shown by block 516, the processor is next operative todetermine whether a predetermined interval, preferably three (3)minutes, has elapsed. If the time interval expired is less than thepredetermined interval, processing returns to block 512. After theelapse of the predetermined interval (or if maximum number of locationshave been found), the processor powers the receiver down as shown byblock 518. Although a three (3) minute sync period to acquire activelocations is presently preferred, other intervals could be employed.

[0175] As shown by block 520, the processor is next operative todetermine if a key has been depressed. If it has, the processor isoperative to handle the keypress and to update system data asappropriate, as shown by block 522. If the key is the sync key,processing branches to block 512, and if the key is the alarm on/offkey, processing jumps to alarm set mode as shown by block 524.

[0176] Otherwise, the processor as shown by block 526 is operative todetermine if the current time is equal to any one (1) of the receptionclocks time's. If it is, the processor is operative to power thereceiver up (and to raise its clock rate) as shown by block 528 and todetermine if data is available as shown by block 530. If it is, theprocessor is operative to determine whether the redundantly transmittedframes match as shown by block 534, and updates system data andcompensates the reception clocks for drift as shown by block 536. Theprocessor is then operative to determine whether the temperature data isout-of-bounds for any active location as shown by block 538 and, if itis, to update system data as shown by block 540 and to power thereceiver down (and lower its clock rate) as shown by block 532. But ifno data is available, or if the redundant frames do not match, or if thetemperature data is not out-of-bounds, the processor is operative topower the receiver down (and lower its clock rate) as shown by the block532.

[0177] Otherwise, the processor is operative to determine whether anyrecords are older than one (1) hour as shown by block 540. If not, theprocessor updates the display as shown by block 544. If they are, theprocessor is operative to blank those records as shown by block 542, andthen to update the display as shown by the block 544. The processor thenhandles other functions, not shown, such as the temperature trendfunction, whereafter processing returns to block 520.

[0178] Many modifications of the presently disclosed invention willbecome apparent to those of skill in the art without departing from theinventive concepts. For example, other modulation methods such asfrequency-shift keying or phase-shift keying could be employed.Different data encoding schemes, weather information other thantemperature such as humidity and/or pressure and/or sun shine, anddifferent duty cycles could also be employed.

What is claimed is:
 1. A single-channel RF weather monitoring anddisplay system displaying information at one location representative ofweather monitored at multiple, other locations remote from said onelocation, comprising: a portable, battery-powered and hand-holdableweather station, deployable at each of said remote locations, includinga housing; a sensor connected to said housing for measuring apredetermined parameter representative of the weather prevailing in theenviron of said sensor at the location where said station may bedeployed; an antenna mounted to said housing; means for setting stationID; and a processor-controlled transmitter mounted in the housing andcoupled to said sensor, said station ID setting means and said antennarepetitively operative (1) to compile a data packet having informationrepresentative of station ID and of said weather parameter sensed bysaid sensor at said location where said station may be deployed, (2) togenerate a unique schedule of at least one transmission times in such away that the unique schedule of at least one transmission times does notoverlap in time with that of other remote locations where portable,battery-operated and hand-holdable weather stations may be deployed and,in accord therewith, to schedule a time to transmit said data packet,and operative (3) to modulate a predetermined-frequency RF carrier waveto transmit said data packet at said scheduled time to enable at saidone location contention-free receipt over said single-channel of datapackets transmitted from said multiple, remote locations where portable,battery-powered and hand-holdable weather stations may be deployed. 2.The single-channel RF weather monitoring and display system displayinginformation at one location representative of weather monitored atmultiple, other locations remote from said one location of claim 1,wherein said unique schedule is a random schedule.
 3. The single-channelRF weather monitoring and display system displaying information at onelocation representative of weather monitored at multiple, otherlocations remote from said one location of claim 1, wherein said uniqueschedule is a schedule of predetermined times.
 4. The single-channel RFweather monitoring and display system displaying information at onelocation representative of weather monitored at multiple, otherlocations remote from said one location of claim 3, wherein saidpredetermined times are determined as two phase schedules consisting ofalternating transmit times defined by {period+phase} and {period−phase}.5. A battery-powered RF weather monitoring and display system,comprising: a portable, battery-powered and hand-holdable weatherstation, deployable at a remote location to monitor a predeterminedweather parameter and transmit the monitored weather parameter to aremote, battery-powered base weather station for display, including ahousing; a sensor connected to said housing for measuring saidpredetermined parameter representative of the weather prevailing in theenviron of said sensor at the location where said portable,battery-powered weather station may be deployed; an antenna; means forsetting station ID; and a processor-controlled transmitter mounted inthe housing and coupled to said sensor and said antenna repetitivelyoperative (1) to compile a data packet having first informationrepresentative of station ID, second information representative of saidweather parameter sensed by said sensor at said location where saidportable, battery-powered and hand-holdable weather station may bedeployed, and third information that enables the remote battery-poweredbase weather station to determine time-of-next transmission allowing thesame to enter battery-power-conserving mode until that time, andoperative (2) to transmit said data packet to said portable,battery-powered base weather station; and a portable, battery-poweredbase weather station operative in response to receipt of a data packettransmitted by said portable, battery-powered and hand-holdable remoteweather station to recover said first information and display saidsensed weather parameter, and to recover said third information and gointo battery power conserving mode until the time of transmission of thenext data packet expected from said portable, battery-powered andhand-holdable remote weather station.
 6. A method of encoding weatherdata at a portable, battery-powered weather station transmitter thatmaximizes detection sensitivity at a base station receiver data slicer,comprising the steps of: defining weather data to be transmitted interms of digital ones and zeros; and encoding the digital ones and zerosof the weather data to be transmitted in terms of first and second codedcombinations of ones and zeros such that none of the ones of the firstand second coded combinations of ones and zeros are adjacent one anotherbut are separated from each other by at least one zero, which preventsripple at said base station receiver data slicer and thereby maximizesits detection sensitivity.
 7. A multiple station weather monitoring andweather information display system, comprising: a transmitter stationincluding at least one probe monitoring first and second weatherparameters and transmitting data representative of the first and secondweather parameters monitored; and a receiver station responsive to saiddata selectably displaying (1) first information representative of saidfirst weather parameter; (2) second information representative of saidsecond weather parameter and (3) third information derived from saidfirst and said second weather parameters in accord with a predeterminedrelation.
 8. The multiple station weather monitoring and weatherinformation display system of claim 7, wherein said first parameter andsaid first information are temperature, said second parameter and saidsecond information are percent relative humidity, and said thirdinformation is heat index.